// 导航栏选项卡
var oNav = $("#nav"),
    aNav = $("span",oNav),
    oContentBox = $("#content_box"),
    aCon = oContentBox.children('div');
aNav.on("click",function(){
    $(this).addClass('nav-active').siblings().removeClass('nav-active');
    var num = $(this).index();
    aCon.css("display","none");
    $(".page"+num).css("display","block");
})
